Agreeing with all of the above, especially the point about seeing the native tokens in these systems as a form of fuel, rather than purely and simply a currency.
Nxt has taken a couple of approaches to mitigate the issue of having to use native NXT tokens to pay tx fees (even if you're only trading/using Nxt-based Assets), and to make it as easy as possible to get native NXT.
The first possibility is to simply sell some of your Assets on the Nxt Asset Exchange, receiving NXT in exchange. Since most Nxt tx cost only 1 NXT, this isn't a massive cost, unless you're running a lot of dust transactions.
Secondly: we integrated a Shapeshift plugin directly into the Nxt client, allowing easy purchase of NXT using any of the crypto-currencies/tokens supported by Shapeshift.
There is a third step coming up to mitigate the "I need Nxt tokens" issue, but that's under wraps right now.
And, you can also look at the Ardor platform: a development of Nxt technology that uses a parent/child multiple blockchain structure.
It will be possible, on Ardor, to create an entire child chain that uses only it's own native token, freeing users of this chain of the need to pay tx fees using Ardor itself.